Safety-brake for elevators.



No. 810,256. PATENTED JAN. 16, 1906.

B. S. BOWMAN.

SAFETY BRAKE FOR ELEVATORS.

APPLICATION FILED JULY 29;19o5.

uvenl'oz Witnesses v I normal position.

BENTON SEAL BOWMAN, OF MILLERSBURG, PENNSYLVANIA.

SAFETY-BRAKE FOR ELEVATORS.

Specification of Letters Patent.

Patented Jan. 16, 1906.

Application filed July 29, 1905. Serial No. 271,719.

To all whom it may concern.-

Be it known that I, BENTON SEAL Bow- MAN, a citizen of the United States of America, residing at Millersburg, in the county of Dauphin and State of Pennsylvania, have invented new and useful Improvements in Safety- Brakes for Elevators, of which the following is a specification.

This invention relates to safety-brakes for elevators, the object of the invention being to provide sim le, reliable, and effective means normally he d out of operation when the hoisting mechanism of the elevator is in working condition, but automatically thrown into ac tion when the hoisting-rope or any of its supports breaks to lock the elevator from downward movement in its shaft.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which- Figure 1 is an elevational view of the elevator guides and brake mechanism, showing the latter applied'to an elevator-car, the latter appearing in transverse section. Fig. 2 is a transverse section through the upper portion of the car, on an enlarged scale, showing the parts of the brake mechanism in their Fig. 3 is a vertical front-torear section on the line 3 3 of Fig. 2. Fig. 4 is a detail view of one of the operating-levers of the brake mechanism, and Fig. 5 is a detail sectional plan view taken on the line 5 5 of Fig. 1.

Referring now more particularly to the drawings, the numeral 1 represents the usual guides vertically disposed in the elevatorshaft, which guides are provided on their inner faces with rack-teeth 2. The car 3 is provided upon its sides with spaced guideflanges 4, which travel on opposite sides of the toothed racks 2. The sides of the carbody extend upwardly beyond the top of the car, as shown at 5, and are connected by and support the head-frame 6. This head-frame 6 comprises a cross bar or board 7, connected at its ends by tie-bolts 8, extending on the outside of the guide-flanges 4 to cross-bars 9, bearing against the bottom of the body of the car. Side plates or boards 10 are disposed upon the bar 7 and extend longitudinally thereof-to form a guideway for operating-levers 11, pivotally connected at their inner ends to a head 12, provided at its upper end with an eyebolt 13 for the attachment of the hoisting-rope 14. From the head 12 depends a guide-stem 15, which is movable in an opening 16 in the bar 7 and is apertured at its lower end below said bar with a transverse opening for the reception of a brake-actuating spring 17. The spring 17 consists of a bowed plate loosely projecting through the opening in the lower end of the stem 15 and extending transversely of the car above the top thereof, the ends of said spring being formed into loops 18 for the reception of guide-pins 19, carried by the ends of the bars 7, such loops being thereby adapted to slide freely on the pins and permit the spring to longitudinally expand and contact. The head 12 also carries guide-arms 20, which project downward on opposite sides of the side boards or plates 10 of the head-frame and are fitted to slide between spaced strips or cleats 21 thereon, the head 12, stem 15, and arms 20 thus forming a vertically-sliding frameconnected with the spring 17 and adapted to operate the levers 11. The weight of the car suspended from the hoisting-rope 14 normally causes the said sliding frame to be elevated to the limit of its upward movement, whereby it holds the spring 17 expanded and the levers 11 at the limit of their inward movement or inoperative. The levers 11 are divergentl y arranged and project downwardly in opposite directions from the head 12, with their outer or free ends traveling in the guide between the said plates or boards 10.

Arranged on opposite sides of the car are toothed dogs or catches 22, adapted to. engage the racks 2. Each of these dogs or catches is free to move toward and from the adjacent rack 2 in guide-notches formed in the extended ends of the bar 7 and is carried by the free end of a shank 23, consisting of a spring-plate projecting downwardly between the guide members or flanges 4. Each springshank 23 may be secured at its lower end to the side of the body of the car in such manner that its upper end, carrying the catch 22, will normally tend to lie between the flanges 4 and hold the catch or dog out of engagement with the rack 2, or the two shanks 23 may be formed of a continuous strip of spring metal extending downward on both sides of the car and across the bottom thereof, as indicated in dotted lines in Fig. 1, the transverse bottom portion of the stri being secured to the bottom of the car, leaving the upper free ends of the terminals of the strips free to be pressed outward into engagement with the racks 2.

The normal position of the parts is shown in Fig. 1, from which it will be seen that the dogs or catches 22 are normally held by their spring-shanks out of engagement with the racks 2, while the weight of the car on the hoisting-rope 14 holds the sliding actuatinghead of the operating-levers elevated with the spring 17 inoperative, thus permitting the car to ascend and descend in the elevatorshaft without interference. If the rope 1 1 or any of its supports should break, the head 12 will be released, and the spring 7 then being unrestrained from movement will expand or bow downward, thus drawing the stem 15 downward with it, whereby the head 12 will be slid in a downward direction to straighten out the levers 11. This operation will cause the outer or free ends of the levers to forcibly project the catches or dogs 22 against the resistance of their spring-shanks 23, whereby said catches will be thrown into engagement with the racks 2 and bring the car to a stop, thus preventing it from dropping downward in the shaft.

It will be seen that the construction of the brake mechanism is simple, that it is e'l'lective for its intended purpose, and that it may be supplied to existing elevators at a com paratively low cost.

Having thus described the invention, what is claimed as new is- 1. In a safety-brake for elevators, the combination of guides provided with toothed racks, an elevator-car, spring-retracted dogs carried by the car to engage said racks, a head-frame fixed to the top of the car and comprising a base and side pieces forming a channeled guideway, a sliding frame having a stem operating in an opening in said base and adapted to be connected with and normally held inoperative by the hoistingrope, a bowed spring disposed below the head-frame and slidably connected at its ends thereto and intermediately to the stem, divergently-arranged levers carried by said sliding frame and movable in thechanneled guideway at their free ends to engage the dogs, and guidepieces carried by the sliding frame to engage the side pieces of the head-frame.

2. In a safety-brake for elevators, the com bination of guides provided with toothed racks, an elevator-car having upward extensions from its sides, spring-retracted dogs carried by the car to engage said racks, a head-frame secured to said extensions and comprising a base and side pieces forming a channeled guideway, a bowed spring ar ranged beneath the base and slidably connected at its ends to the head-frame or extensions, a vertically-movable frame having a stem projecting through an opening in the base of the head-frame and intermediately connected with the bowed spring, said frame being adapted for connection with the hoisting-rope, divergently-arranged levers connected with said vertically-movable frame and movable in the channeled guideway to engage and project the dogs, and guide-pieces carried by said vertically-movable frame to engage the sides of the head-frame.

In testimony whereof I aflix my signature in presence of two witnesses.

BENTON SEAL BOWMAN.

Witnesses:

A. M. CRoLL, WM. A. CRoLL. 

